May 7, 2009 -- New research suggests that probiotics -- widely viewed as "friendly" bacteria that improve digestion and gut health -- may help women keep belly fat under control after pregnancy.

Researchers from the University of Turku in Finland enrolled 256 pregnant women in a study on weight gain, dividing them into three groups during their first trimesters.

Women in two of the groups received dietary counseling consistent with what doctors recommend for healthy weight gain and optimal fetal development.

They also were sent home with foods such as spreads and salad dressings with monounsaturated and polyunsaturated fatty acids, as well as fiber-enriched pasta and breakfast cereal.

Women in one of those two groups also received daily capsules containing lactobacillus and bifidobacterium, the most commonly used probiotics -- bacteria that help maintain a healthy bacterial balance in the gut. The other group received dummy capsules along with counseling.

A third group received dummy capsules and got no dietary counseling.

All of the women were weighed at the start of the study. They were weighed again at 12 months after childbirth; researchers then measured each woman's waist circumference and skin fold thickness.

Central obesity -- defined as a body mass index of 30 or more and a waist circumference over 80 centimeters (31.5 inches) -- was found in 25% of the women who had been given the probiotics as well as advice on what to eat.

Those not given probiotics didn't do as well. Central obesity was found in 43% of the women who got dietary counseling alone and 40% of the women who got neither probiotics nor dietary advice.

The average body fat percentage in the probiotics group was 28%, compared with 29% in the diet-advice-only group and 30% in the third set of women.

"The women who got the probiotics fared best," says Kirsi Laitinen, a nutritionist and senior lecturer at Turku. "One year after childbirth, they had the lowest levels of central obesity as well as the lowest body fat percentage."

She adds that more research is needed to confirm the potential positive role of probiotics on belly fat. Also, she says her team of researchers will continue to track the women and their babies to determine whether giving probiotics during pregnancy has any influence on the health of the children.

The findings were released during the 17th European Congress on Obesity in Amsterdam, Netherlands.